



Il. the object of retarding thaouw wavais oamgiiad. Inthailinstravaamtbe ratartianis iso aleman! duren as shown by assauts sertion of an extra reset pulse into the multivibrator I2 will enect an advance of phase of the output wave.

What is claimed is:

l. Phase shifting apparatus comprising means to provide an alternating current input signal of square wave form, a plurality of multivibrainrsrpsrforming a man divhicn on said dgnal whereby to provide an oumut signal from said multivibrators. a feedback link for feeding :met pulses from one of said multivibrators to another, and means responsive to a retarding signal for interrupting transmission oi said reset miss 'bushy to rstard the phase of said output 2. Ph* iftim apparatus comprising means to provide an alternating current input signal of square wave form. a chain of two coupled stable maltivibrators for performing a frequency division on said signal, said chain normally dividlngaaidsignalfrsoueucybyiour. afeadback iinktorfeedingrssetpulseafmmonemulsivibra tortoibeothenwherebytoprovideanoubut signal from said multivibratcrs of a frequency whichisone-thirdofthefrequencyoftham signaLandmeansrspomiveto a retardisigmi for interrupting transmision ot said raast pulses whereby toretard thephaseofsaidoub a. :hase shifting spparat comprising msaas to provide an alternating ourrant input signal of square wave form. a multivibrator hamm two stable conditions of operation. means to am said input signal to said multivibrator. a saws!! multivibrator having two liable conditions of operation. means to couple the output of .l nrst multivibrator to mid second multivibratm, a feedback oonnscuon from mid second .altivibrator to said nrst multivibrator whereby to alter the frequency division of mld multivibratoraathirdmnitivibratorottbeunbaianosd typameanstolwbnubstosaidthirdsmtivibrator in accordance with retard information. and means operating under control of said third multivibrator for disabim uid feedbad oonnecidnn during the time d reversal of said third multivibrator whereby to retard the phase ed tha output sigml Imm laid second multivibrator.

4. Phase shifting apparatus comprising ma to provide an alternatim current input signal of square 'ava form. a multivibrator :having two stable conditions of operation. means to awiy said input signal to said multivibrator. a ssoond multivibrator having two stable conditions ot operatiommeanstoooupiethooutputotmid met multivibrator to said second muitivrss, a feedback connection including a vacuum taba from said second multivibrator to said nrst moitivibratorwherebytoalterthefmuenoydivisn ci said multivibratcrs. a third multivibrator d the unbalanced type. means to apply pulsas to said third multivibrat in aooordanoa with ratard information, and moans operating mida' control of mld third milvibrator for biasmg said vacuum tubo below cutoff during tbs tuna of reversal of said third multivibrator wharaby tcretardthephaseoftheontputaignalfromsaid second multivibrator.

5. Phase shifting apparatus comprising means to provide an alternating current input signal of square wave form. a multivibrator having two stable conditions of operation. moans to apply said input signal to said multivibrator. a eond multivibrator' having two stable conditions af operation. moans to wie the output 

